1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a structure of fixing a printed circuit board on a liquid crystal display panel and a method for fixing thereof that provide an insulating film to protect the printed circuit board and fix the printed circuit board without a hook or a screw.
2. Discussion of the Related Art
A display device is considered to be more and more important as visual information transmission increases. In addition, as display devices being increasing used in portable devices, they need to have high resolution images, lightness, thin profile, compact size, and low power consumption.
In general, display devices are classified into a light-emitting type or a non-light-emitting type. The light-emitting type display devices include cathode ray tube (CRT) devices, electro-luminescent (EL) devices, light emitting diode (LED) devices, vacuum fluorescent display (VFD) devices, field emission display (FED) devices, and plasma display panel (PDP) devices, which emit light by themselves. The non-light emitting type display devices include liquid crystal display (LCD) devices, which cannot emit light by itself.
LCD devices use the optical anisotropy and polarization properties of liquid crystal molecules to generate a desired image. In particular, liquid crystal molecules can be aligned in a specific orientation, which can be controlled by applying an electric field across the liquid crystal molecules. Due to optical anisotropy, incident light is refracted according to the orientation of the liquid crystal molecules, thereby generating the desired image.
FIG. 1 is a disassembled perspective view schematically showing a liquid crystal display device according to the related art. In FIG. 1, a liquid crystal display device includes a liquid crystal display panel 10, driving circuit units 20 and 30, and a backlight unit 40, which are enclosed by an upper case 50 and a lower case 60. Although not shown, the liquid crystal display panel 10 includes an array substrate, a color filter substrate, and a liquid crystal layer formed between the array substrate and the color filter substrate.
In addition, the driving circuit units 20 and 30 supply driving signals to the liquid crystal display panel 10 for displaying an image on the liquid crystal display panel 10. The driving circuit units 20 and 30 include printed circuit boards 21 and 31 to which tape carrier packages (TCP) 22 and 32 are attached, respectively. The tape carrier package 22 is a gate tape carrier package, and the tape carrier package 32 is a data tape carrier package. Although not shown, the driving circuit units 20 and 30 also include other devices, such as a timing controller, a data driver integrated circuit (IC) mounted on the data tape carrier package 32, and a gate driver integrated circuit mounted on the gate tape carrier package 22.
The backlight unit 40 is at a rear side of the liquid crystal display panel 10 and emits light onto the liquid crystal display panel 10. In addition, the backlight unit 40 includes a lamp assembly including a fluorescent lamp (not shown) for generating light, a reflection sheet 41 for reflecting light emitted from the fluorescent lamp, a light guide plate 42 for guiding the reflected light, and a plurality of optical sheets 43 for diffusing and collecting light transferred from the light guide plate 42. Further, the backlight unit 40 is mounted in a mold frame 44.
Further, the data tape carrier package 32 is bent to position the data printed circuit board 31 at a rear surface of the liquid crystal display panel 10. In addition, the gate tape carrier package 22 is bent once. Since the gate printed circuit board 21 generally is small, the gate printed circuit board 21 is positioned along a side surface of the mold frame 44 by bending the gate tape carrier package 22 once. By positioning the gate printed circuit board 21 along the side surface of the mold frame and positioning the data printed circuit board 31 at the rear surface of the liquid crystal panel 10, a display area of the liquid crystal display panel 10 is increased.
FIG. 2A is a planar view of a portion of a rear side of a liquid crystal display device without a lower case according to the related art. In FIG. 2A, the data printed circuit board 31 is attached and affixed to the mold frame 44 by a hook H. By forming the hook H at a predetermined portion of the mold frame 44 and inserting the data printed circuit board 31 into a lower portion of the hook H, the data printed circuit board 31 is affixed on the mold frame 44. However, in a process of assembling and disassembling the printed circuit board 31, the tape carrier package 32 or a chip-on-film (COF) attached to the printed circuit board 31 can be damaged easily. Thus, it typically takes longer time to assemble or disassemble a printed circuit board, which is affixed by a hook. In addition, whenever the hook needs to be removed, the printed circuit board also can be damaged by the process.
FIG. 2B is a planar view of a portion of a rear side of another liquid crystal display device according to the related art. In FIG. 2B, the data printed circuit board 31 is attached and affixed to the mold frame 44 by screws S. By fastening the screws S through the data printed circuit board 31 at predetermined portions of the mold frame 44, the data printed circuit board 31 is affixed on the mold frame 44. However, it typically takes longer time to ensure the screws S are securely fastened, thereby increasing an operator's work load and reducing productivity.